Direct Photoassisted α‐Trifluoromethylation of Aromatic Ketones with Trifluoroacetic Anhydride (TFAA).

Direct α‐Trifluoromethylation of acetophenone derivatives was achieved by using trifluoroacetic anhydride (TFAA) as the trifluoromethyl source and pyridine‐N‐oxide (Py−O) as activator and oxidant under visible light irradiation and tris‐(2,2′‐bipyridine)ruthenium(II) hexafluorophosphate (Ru(bpy)3(PF6)2) as the photocatalyst. Different acetophenone derivatives could be converted to the corresponding α‐CF3 derivatives with high selectivity. Extensive mechanistic investigation revealed the formation of vinyl trifluoroacetate as the key intermediate for this transformation. [ABSTRACT FROM AUTHOR]